A PERF solution for distributed query optimization

Query optimization techniques aim to minimize the cost of transferring data across networks. Many techniques and algorithms have been proposed to optimize queries. One of the algorithms is the W algorithm using semi-joins. Nowadays, a new technique called PERF seems to bring some improvement over semi-joins [2]. PERF joins are two-way semi-joins using a bit vector as their backward phase. Our research encompasses applying PERF joins to the W algorithm. Programs were designed to implement both the original and the enhanced algorithms. Several experiments were conducted and the results showed a very considerable enhancement obtained by applying the PERF concept.